Production method for laminate type dielectric device and electrode paste material

ABSTRACT

This invention provides a method of producing a laminate type dielectric device free from peeling of an electrode layer and a ceramic layer and from voids in both electrode layer and ceramic layer, and an electrode paste material. The invention relates also to an electrode paste material for constituting electrode layers of a laminate type dielectric device produced by at least the steps of alternately laminating ceramic layers  11  containing a lead element as a constituent component and electrode layers  2 , and degreasing and baking the laminate, wherein the electrode paste material contains CuO as a principal component of a starting material of an electrically conductive material, a solvent, a binder, and a cooperative material consisting of at least one kind of the main components constituting the ceramic layer  11.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to production method for a laminate typedielectric device such as a laminate type capacitor, a laminate typepiezoelectric actuator, etc, and an electrode paste material for formingelectrode layers in the dielectric device.

[0003] 2. Description of the Related Art

[0004] Laminate type dielectric devices produced by alternatelylaminating dielectric ceramic layers having various dielectricproperties and electrode layers have been widely used in the past. Knownelectrode materials for forming these electrode layers include Pt, Pd,Ag, Ni, Cu, their mixtures and their alloys.

[0005] The problems encountered in producing the electrodes vary fromelectrode material to electrode material. Silver (Ag), for example, hasa high electric conductivity and is relatively economical. However, Aghas a low melting point of 980° C., is likely to invite migration andtherefore has low reliability.

[0006] In contrast, palladium (Pd) is expensive but has a high meltingpoint. Pd has therefore been used in the form of an Ag-Pd metal materialto suppress migration and to improve the melting point of the electrodematerial (refer to Japanese Unexamined Patent Publication (Kokai) No.5-304043).

[0007] The addition of Pd can suppress migration, it is true, butbonding is not sufficient between the electrode material and a ceramicmaterial. Various measures have been taken to cope with this problem asdescribed in Japanese Unexamined Patent Publications (Kokai) Nos.5-304043 and 8-255509.

[0008] Nickel (Ni) involves problems such as the occurrence of crackingand deformation and so-called “islanding” of the electrode due tosuperheating (rapid sintering of Ni at a temperature exceeding 1,000°C.). To cope with the problems, Japanese Unexamined Patent Publication(Kokai) No. 5-55077 proposes to mix Ni and NiO, and Japanese UnexaminedPatent Publication (Kokai) No. 6-290985 proposes to add an oxide of arare earth element.

[0009] Among them, the prior art technology using Ag aims at solving theproblem that results from Ag, and the prior art technology using Ni, atsolving the problem of superheating of Ni that is peculiar to Ni.However, these technologies for producing the electrode are expensivedue to the expensive additives and the machining cost. So long as thesematerials are used, reduction of the production cost of the laminatetype dielectric device that has widely been used will be difficult.Further, technologies in the case of Ag and Ni cannot be easily appliedto Cu.

[0010] On the other hand, copper (Cu) could be a promising materialamong base metals as the economical electrode material. In connectionwith Cu-containing paste materials or electrodes, a technology is knownthat suppresses the occurrence of cracking resulting from oxidationexpansion of Cu by mixing Cu and Cu₂O at a suitable proportion (JapaneseUnexamined Patent Publication (Kokai) No. 5-283274). Further, there arealso known a method that forms a complex by using an organic phosphoruscompound and a metal (Cu) ion, and baking the complex to assistsintering of ceramics and to make the film thickness uniform (JapaneseUnexamined Patent Publication (Kokai) No. 5-242724), and a method thatsuppresses the occurrence of warp and cracking of the device by limitingthe Cu content to 40 to 70 wt % to reduce the coating thickness(Japanese Unexamined Patent Publication (Kokai) No. 5-234414).

[0011] Still another known technology uses a paste material containing40 to 60 wt % of Cu powder having a mean particle diameter of 0.5 to 2μm and a particle size distribution of 0.3 to 4 μm and bakes the pastematerial to a film thickness of 1 to 3 μm so as (1) to suppress theoccurrence of voids between the device and the electrode and inside theelectrode, (2) to suppress the occurrence of breakage of the electroderesulting from warp of inner and outer electrodes, (3) to preventdeformation of a ceramic component itself and (4) to prevent inferiorcontact between the inner electrode and the outer electrode (JapaneseUnexamined Patent Publication (Kokai) No. 5-190375). In this way, themethods and objects of using Cu electrodes are very diversified.

[0012] As an example relating to a Cu electrode or a Cu type pastematerial, Japanese Unexamined Patent Publication (Kokai) No. 5-275263describes the addition of at least one kind of the principal componentsof the ceramic layer or a material having substantially the samecomposition as the ceramic layer (hereinafter called the “base” of theceramic layer or the “cooperative material”). The cooperative materialdesignated in this prior art reference needs a specific processing ofadding inorganic powder the surface of which is coated with a metal ofthe same kind as metal powder of the electrode. The object of thistechnology is to inhibit sintering of the metal so as to preventdiscontinuity of the electrode and the increase of the resistance. Tosolve the fundamental problem that sintering of Cu proceeds more quicklythan sintering of the ceramic material, this reference attempts toretard sintering by impeding sintering of the metal and to avoiddiscontinuity of the electrode.

[0013] Another example of the addition of the cooperative material ofthe ceramic layer is described in Japanese Unexamined Patent Publication(Kokai) No. 64-89311. This technology relates to an internal electrodepaste for a laminate ceramic body, and describes the addition of thesame compound as the ceramic material of the ceramic body. However, theconstruction of the electrode paste material is not CuO, as used in thepresent invention as will be described later, but is Cu₂O.

[0014] In the case of the paste material consisting of CuO, large volumeshrinkage occurs when CuO is reduced to metallic copper with the resultof the occurrence of cracks in the sintered body, and de-lamination dueto the occurrence of voids between the ceramic layer and the electrodelayer. To solve this problem, the reference describes Cu₂O as asubstitution. The cooperative material of the ceramic layer is utilizedto improve bondability between the inner electrode layer and the ceramiclayer. In other words, this reference solves the problem of shrinkage ofthe Cu oxide in the electrode paste material by using Cu₂O in place ofCuO, and utilizes the cooperative material of the ceramic layer toimprove bondability between the ceramic layer and the electrode layer.

[0015] Another example that uses the cooperative material of the ceramiclayer is described in Japanese Unexamined Patent Publication (Kokai) No.2-22806 that relates to a laminate ceramic capacitor.

[0016] In the case of this laminate ceramic capacitor, too, thereference describes that the cooperative material of the ceramic layeris to impart de-lamination resistance. Examples of this reference use acopper paste (metal paste) but do not use CuO. The reference does notpresent the technical significance of the addition of the cooperativematerial of the ceramic layer.

[0017] Production of a laminate type dielectric device is not easy whenthe copper (metal) paste described in the Laid-Open Patent Publicationdescribed above is used.

[0018] For, the production process for producing the laminate byapplying the paste material includes (1) degreasing, (2) metallizing,that is, a reducing step of the electrode material from CuO to Cu whenthe laminate is produced by using a CuO paste material, and (3) baking.

[0019] When the copper (metal) paste as the electrode paste material isused to produce the laminate, degreasing must be carried out in thereducing atmosphere to avoid peeling resulting from oxidation of copper(involving expansion). Degreasing is the step of dissolving and removinga binder, and the like, and when chemically expressed, it is theoxidation of carbon, and the like. Therefore, when degreasing is carriedout in the reducing atmosphere, a longer processing time is necessarythan degreasing in normal open air because the oxygen content is small.

[0020] Unless degreasing is sufficiently done, the remaining carbonreacts with oxygen and exerts adverse influences in the subsequentbaking step in the reducing atmosphere. For example, because carbon islikely to remain at the center of the laminate, a difference in theatmosphere occurs between the outer peripheral portion and the centerportion during reduction/baking even inside the same laminate typedielectric device, and the drop of displacement performance, or thelike, partially develops with diffusion resulting from oxidation of theelectrode or the reduction of the ceramic layer. On the other hand,complete degreasing is not practical because a longer time is necessary.

[0021] For the reasons described above, a paste material of copper oxidecapable of being degreased even in the oxidizing atmosphere isadvantageous as the electrode paste material for forming the electrodelayers of the dielectric device produced by alternately laminatingceramic layers containing a lead element as the constituting componentand the electrode layers.

[0022] As a matter of fact, when the CuO paste material is applied andlaminated with the ceramic material, is then degreased, metallized(reduction of CuO of the electrode material to Cu) and baked, peelingdoes not occur between the electrode portions and the ceramic layers butvoids develop in the electrode portions. When the CuO content in the CuOpaste material is increased to solve this problem, the voids in theelectrode portions can be eliminated and the continuous electrode layercan be formed, but voids develop in the ceramic layer.

SUMMARY OF THE INVENTION

[0023] In view of the problems of the prior art described above, thepresent invention aims at providing a production method of a laminatetype dielectric device which is free from the occurrence of peelingbetween electrode layers and ceramic layers and free from the occurrenceof voids in both electrode layers and ceramic layers, and an electrodepaste material.

[0024] According to a first aspect of the present invention, there isprovided an electrode paste material for forming electrode layers of alaminate type dielectric device produced by at least the steps ofalternately laminating ceramic layers containing a lead element as aconstituent component and electrode layers, degreasing and baking,wherein the electrode paste material contains CuO as the principalcomponent of the starting material of an electrically conductivematerial, a solvent, a binder, and a cooperative material consisting ofat least one of the principal components constituting the ceramiclayers.

[0025] Next, the function and effect of this invention will beexplained.

[0026] The electrode paste material of the present invention containsCuO as the principal component and the cooperative material as describedabove. Therefore, the CuO content in the electrode paste material can beeasily adjusted.

[0027] In other words, when the cooperative material is not alsocontained, it is possible to obtain an electrode paste material freefrom the occurrence of voids and peel after baking and having an optimumCuO content. However, when the cooperative material is not contained,the electrode paste material quickly changes to the one that invitesdisadvantages such as voids and peeling if the CuO content deviates evenslightly from the optimum CuO content. Therefore, adjustment of the CuOcontent is extremely difficult.

[0028] In contrast, the CuO content in the electrode paste material canbe easily adjusted in the present invention because the electrode pastematerial contains the cooperative material as described above. In otherwords, the co-presence of the cooperative material can drasticallyenlarge the width of the optimum range of the CuO content, and canminimize the influences resulting from fluctuation of the CuO content.

[0029] Therefore, the electrode paste material having excellent qualitycan be adjusted, and when this electrode paste material is used, anexcellent laminate type dielectric device free from the disadvantagessuch as cracks, voids and peeling can be easily produced.

[0030] Since this electrode paste material is mainly made of Cu as theelectrically conductive material, the production cost becomes less thanfor the conventional electrode paste material using a precious metal forthe electrode layer.

[0031] To obtain high performance in a laminate product obtained byusing a ceramic material containing a Pb element as a constituentcomponent and a Cu electrode material, it is necessary to sufficientlyreduce the Cu electrode paste material and to form an electrode layerhaving high conductivity such as a Cu metal. Therefore, a processing ina reducing atmosphere becomes necessary.

[0032] On the other hand, when the ceramic material is reduced, meltingoccurs due to the eutectic reaction with Cu. Therefore, the reducingatmosphere must be adjusted to an atmosphere that does not reduce theceramic material but reduces the Cu type material in the electrode pastematerial.

[0033] When the binder remains in the laminate product during theprocess step described above, carbon emitted from the binder reacts withoxygen and impedes adjustment of the atmosphere. When adjustment of theatmosphere is impeded, reduction of a part of the ceramic materialoccurs, and melting occurs due to the eutectic reaction with Cu.

[0034] Therefore, in the step of adjusting the reducing atmosphere, asample that is sufficiently degreased (from which the binder is removed)is necessary.

[0035] If the eutectic reaction between the reduction product of a partof the ceramic material and Cu occurs belatedly (when the eutectic pointis high), incomplete degreasing is permitted to a certain extent.

[0036] For example, when the eutectic point of the reduction product andCu is higher than the highest temperature of the degreasing condition,degreasing is substantially conducted again at a temperature lower thanthe eutectic point in the subsequent process steps, and the binder thatremains to a certain extent in the degreasing step can be thusevaporated without any problem.

[0037] On the other hand, when the ceramic material partly contains a Pbelement as a constituent component, melting of Pb and Cu formed by thereduction occurs at a low eutectic point of 326° C. Therefore,degreasing must be completely terminated in the degreasing step.

[0038] To more completely attain degreasing, an atmosphere havingsufficient oxygen becomes necessary because degreasing is oxidation ofthe binder.

[0039] To degrease the laminate product applied with the electrode pastematerial in the atmosphere having sufficient oxygen, expansion resultingfrom oxidation of the electrode material in the electrode paste materialmust be suppressed. To cope with this problem, an oxide such as CuO mustbe contained as one of the principal components of the paste material.

[0040] Further, the function when the cooperative material is containedwill be explained in detail.

[0041] When the electrode paste material is applied to the green sheetfor forming the ceramic layer and these members are laminated andintegrally baked, sintering or a reaction occurs at three positions,that is, sintering of the ceramic layer, sintering of the electrodelayer and sintering of their boundary portion. Among them, sintering ofthe boundary portion between the electrode layer and the ceramic layeris believed to occur most rapidly at a low temperature due to thereaction of the Cu electrode material or CuO existing as the oxide filmof Cu oxide or Cu₂O formed by partial reduction of CuO and the oxidecontained in the ceramic layer at the eutectic point. Therefore, it isbelieved that peeling occurs with difficulty at this portion.

[0042] For this reason, the degree of progress of sintering of each ofthe electrode portion (electrode layer) and the ceramic layer and thedegree of shrinkage of each member can be a problem. Generally,sintering of the electrode portion proceeds more quickly (at a higherrate) than that of the ceramic layer. Therefore, shrinkage (in a broadersense of the word inclusive of occurrence/extinction of voids due toevaporation of solvent and binder; hereinafter the same) of theelectrode portion is greater than shrinkage of the ceramic layer, andvoids are more likely to develop in the electrode portion. On the otherhand, when the CuO content in the electrode paste material is increased,the electrode can be continuously formed without voids, but cracks(voids) develop in the ceramic layer. At this time, shrinkage due tosintering of the electrode portion becomes small, and the shrinkageratio of the ceramic layer becomes relatively great.

[0043] A laminate product free from voids in both the electrode layerand the ceramic layer can be formed when the CuO content in theelectrode CuO type paste material is adjusted to a suitable content. Atthis time, if the cooperative material of the ceramic layer is added inadvance to the electrode CuO type paste material, a laminate product canbe formed at the same CuO content, at which the laminate product freefrom voids in both electrode/ceramic layers can be formed without theaddition of the cooperative material, and can be formed even when theCuO content is greater by several percents. In other words, a laminateproduct can be formed at a CuO content at which voids develop in theceramic layer unless the cooperative material is added.

[0044] The phenomenon described above can be interpreted in thefollowing way. When the cooperative material of the ceramic layer isadded in advance to the electrode CuO type paste material, sintering iscompleted while the cooperative material of the ceramic layer addedremains inside the electrode portion or in the boundary portion betweenthe electrode portion and the ceramic layer, and a laminate product freefrom voids in both the electrode and the ceramic layers can be formedprovided that the degree of progress of the electrode layer and itsdegree of shrinkage fit those of the ceramic layer. In other words, alaminate product can be formed at the same CuO content as the CuOcontent when the cooperative material of the ceramic layer is not added.

[0045] When the cooperative material of the ceramic layer is added tothe paste material having a CuO content greater by several percents byweight than the CuO content of the case described above, the occurrenceof voids in the ceramic layer can be suppressed because the cooperativematerial of the ceramic layer added into the electrode portion movesinto the ceramic layer and adjusts the degree of shrinkage at a point oftime when the degree of shrinkage of the ceramic layer becomesrelatively great with the temperature rise, or within the temperaturerange near that point.

[0046] Next, a second aspect of the invention provides a method ofproducing a laminate type dielectric device by at least the steps ofalternately laminating ceramic layers containing a lead element as aconstituent component and electrode layers, and degreasing and bakingthe laminate, comprising preparing green sheets obtained by shaping aceramic material into a sheet form, and an electrode paste materialcontaining CuO as a principal component of a starting material of anelectrically conductive material, a solvent, a binder, and a cooperativematerial consisting of at least one kind of the main componentsconstituting the ceramic layer; applying the electrode paste material toat least one of the surfaces of the plurality of green sheets; andlaminating the green sheets, and then conducting degreasing and baking.

[0047] It is noteworthy in this production method that the electrodepaste material consisting of CuO as the principal component andcontaining the cooperative material is used.

[0048] When this electrode paste material is used, adjustment of CuOcontent becomes extremely easy as described above. Therefore, anexcellent laminate type dielectric device free from peeling of theelectrode layer and the ceramic layer and free from voids in both theelectrode and the ceramic layers can be easily obtained.

[0049] Next, the application of the electrode paste material describedabove can be made to both surfaces of the green sheet, and the electrodepaste material can be brought into mutual contact in the laminationstep. In this case, the electrode paste material can be brought intomutual contact when the green sheets are laminated, and a quick reactioncan be achieved in the subsequent baking process.

[0050] Further, a metallic foil having electrical conductivity can beinterposed between the electrode paste materials. In this case, evenwhen the component composition of the electrode paste material is suchthat the electrode layer is likely to disappear after baking, themetallic foil can reliably secure the conductive portion.

[0051] Next, the cooperative material described above preferably hassubstantially the same composition as that of the ceramic layer.Consequently, adhesion between the ceramic layer and the electrode layercan be further improved.

[0052] Further, the content of CuO is preferably greater than 30 wt %but less than 82.5 wt %, and the content of the cooperative material isgreater than 0.5 wt % but is less than 25 wt %.

[0053] Preferably, the CuO content is not less than 40 wt % but notgreater than 77.5 wt %.

[0054] The content of the cooperative material is preferably not lessthan 1 wt % but not greater than 15 wt %.

[0055] When the CuO content is not greater than 30 wt %, the problemoccurs that voids develop in the electrode layer after baking.Therefore, the CuO content is more preferably 40 wt % or more. On theother hand, when the CuO content is 82.5 wt % or more, the problemdevelops that cracks (voids) develop in the ceramic layer. Therefore,the CuO content is more preferably not greater than 77.5 wt %.

[0056] When the content of the cooperative material is 25 wt % or more,the problem develops that the electrode layer is interrupted and becomesnon-conductive. Therefore, the content of the cooperative material ismore preferably not greater than 15 wt %.

[0057] When the content of the cooperative material is not greater than0.5 wt %, the effect of suppressing cracks in the ceramic layer cannotbe acquired. Therefore, the content of the cooperative material is morepreferably at least 1 wt %.

[0058] Further, the ceramic layer can use PZT mainly made of an oxidehaving a Pb(Zr, Ti)O₃ type perovskite structure. This PZT exhibitsextremely excellent properties as a dielectric.

[0059] Next, a third aspect of the invention provides an electrode pastematerial for constituting electrode layers of a laminate type dielectricdevice produced by at least the steps of alternately laminating ceramiclayers containing a lead element as a constituent component and theelectrode layers, and degreasing and baking the laminate, wherein theelectrode paste material contains CuO and Cu as principal components ofa starting material of an electrically conductive material, a solvent, abinder, and a cooperative material consisting of at least one kind ofthe main components constituting the ceramic layer.

[0060] In the present invention, a starting material of an electricallyconductive material contains Cu in addition to CuO described above.Therefore, expansion resulting from expansion of oxidation of Cu in thedegreasing step can be suppressed, and shrinkage of CuO due to itsmetallization in the reducing/baking steps can be suppressed, too.

[0061] Besides, the same function and effect as that of the first aspectof the invention can be obtained.

[0062] Next, a fourth aspect of the invention provides a method ofproducing a laminate type dielectric device by at least the steps ofalternately laminating ceramic layers containing a lead element as aconstituent component and electrode layers, and degreasing and bakingthe laminate, comprising preparing green sheets obtained by shaping aceramic material into a sheet form, and an electrode paste materialcontaining CuO and Cu as principal components of a starting material ofan electrically conductive material, a solvent, a binder, and acooperative material consisting of at least one kind of the maincomponents constituting the ceramic layer; applying the electrode pastematerial to at least one of the surfaces of the plurality of greensheets; and laminating the green sheets, and then conducting degreasingand baking.

[0063] In this invention, too, a starting material of the electricallyconductive material contains Cu in addition to CuO as the principalcomponents. Therefore, expansion resulting from oxidation of Cu in thedegreasing step can be suppressed, and shrinkage due to metallization ofCuO in the reducing/baking steps is suppressed, too. A laminate typedevice can be produced without any problem if CuO is metallized beforebaking. However, if metallization when the baking is not sufficient,shrinkage takes place at a high temperature (during or after baking),and voids develops in the electrode layer. Because Cu and CuO are usedas the principal components, the necessary amount of metallization isdecreased, and the void occurrence ratio of the electrode layer can beeasily suppressed.

[0064] Beside, the same function and effect as that of the second aspectof the invention can be obtained.

[0065] Next, the application of the electrode paste material can be madeto both surfaces of the green sheet, and the electrode paste materialcan be brought into mutual contact in the lamination step. In this case,the electrode paste materials can be brought into mutual contact in thelamination step of the green sheets, and the quick reaction can beobtained in the subsequent baking step.

[0066] Further, a metallic foil having electrical conductivity can beinterposed between the electrode paste materials. In this case, evenwhen the component composition of the electrode paste material is suchthat the electrode layer is likely to disappear after baking, themetallic foil can reliably secure the conductive portion.

[0067] Preferably, the cooperative material described above hassubstantially the same composition as that of the ceramic layer.Consequently, adhesion between the ceramic layer and the electrode layercan be further improved.

[0068] Further, the total content of CuO and Cu is preferably greaterthan 30 wt % but less than 82.5 wt %, and the content of the cooperativematerial is greater than 0.5 wt % but is less than 25 wt %. However, thetotal content of CuO and Cu in the invention represents the amountcalculated to CuO in terms of the proportion of the molecular weight.

[0069] Preferably, the total content of CuO and Cu is not less than 40wt % but not greater than 77.5 wt %.

[0070] Further, the content of the cooperative material is preferablynot less than 1 wt % but not greater than 15 wt %.

[0071] When the total content of CuO and Cu is not greater than 30 wt %,the problem occurs that voids develop in the electrode layer afterbaking. Therefore, the total content of CuO and Cu is more preferably atleast 40 wt %. On the other hand, when the total content of CuO and Cuis 82.5 wt % or more, a problem occurs that cracks (voids) develop inthe ceramic layer. Therefore, the total content of CuO and Cu is morepreferably not greater than 77.5 wt %.

[0072] When the content of the cooperative material is not less than 25wt %, the problem occurs that the electrode layer is interrupted andbecomes non-conductive. Therefore, the content of the cooperativematerial is more preferably not greater 15 wt %.

[0073] When the content of the cooperative material is not greater than0.5 wt %, the effect of suppressing cracks in the ceramic layer cannotbe acquired. Therefore, the content of the cooperative material is morepreferably at least 1 wt %.

[0074] Further, the ceramic layer can use PZT mainly made of an oxidehaving a Pb(Zr, Ti)O₃ type perovskite structure. This PZT exhibitsextremely excellent properties as a dielectric.

BRIEF DESCRIPTION OF THE DRAWINGS

[0075]FIG. 1 is an explanatory view showing a production process of alaminate type dielectric device according to Embodiment 1;

[0076]FIG. 2 is a perspective view showing the laminate type dielectricdevice in Embodiment 1;

[0077]FIG. 3 is an explanatory view showing an observation result of asection of Sample 1 in Embodiment 1;

[0078]FIG. 4 is an explanatory view showing an observation result of asection of Sample 7 in Embodiment 1;

[0079]FIG. 5 is an explanatory view showing an observation result of asection of Sample 8 in Embodiment 1;

[0080]FIG. 6 is an explanatory view showing an observation result of asection of Sample 9 in Embodiment 1;

[0081]FIG. 7 is an explanatory view showing an observation result of asection of Sample 10 in Embodiment 1;

[0082] FIGS. 8(a) and 8(b) are explanatory views showing observationresults of sections of Samples 11 and 12 in Embodiment 1, respectively;

[0083]FIG. 9 is an explanatory view showing an observation result of asection of Sample 13 in Embodiment 1;

[0084]FIG. 10 is an explanatory view showing an observation result of asection of Sample 14 in Embodiment 1;

[0085]FIG. 11 is an explanatory view showing an observation result of asection of Sample 15 in Embodiment 1;

[0086]FIG. 12 is an explanatory view showing an observation result of asection of Sample 16 in Embodiment 1;

[0087]FIG. 13 is an explanatory view showing an observation result of asection of Sample 14 in Embodiment 2; and

[0088]FIG. 14 is a perspective view showing a piezoelectric actuatoraccording to Embodiment 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0089] Embodiment 1:

[0090] A production method of a laminate type dielectric device and anelectrode paste material according to Embodiment 1 will be explainedwith reference to FIGS. 1 to 12.

[0091] In this embodiment, sixteen kinds of Samples 1 to 16 as electrodepaste materials are first prepared as tabulated in Table 1. TABLE 1 (wt%) Organic vehicle Cooperative Sample No. and resin CuO powder material 1 31.0 61.0 8.0  2 31.0 65.0 4.0  3 31.0 66.0 3.0  4 31.0 68.0 1.0  529.0 67.0 4.0  6 27.0 69.0 4.0  7 36.0 64.0 nil  8 35.0 65.0 nil  9 33.566.5 nil 10 31.0 69.0 nil 11 50.0 50.0 nil 12 44.0 50.0 6.0 13 40.0 50.010.0 14 19.5 77.5 3.0 15 14.5 82.5 3.0 16 17.5 82.5 nil 17 45.0 40.015.0 18 55.0 30.0 15.0 19 35.0 40.0 25.0 20 31.0 68.5 0.5

[0092] The electrode paste materials of Samples 1 to 6 all contain CuOas the principal component of a starting material of an electricalconductive material, a solvent, a binder and a cooperative materialconsisting of at least one kind of principal components of a ceramicmaterial constituting the ceramic layer. The CuO content is within therange of 61 to 69 wt % and the content of the cooperative material isnot greater than 8 wt %.

[0093] Samples 7 to 10 do not contain the cooperative material.

[0094] In Samples 11 to 13, the content of CuO is limited to 50 wt %. InSample 11, the cooperative material is not added. In Samples 12 and 13,the cooperative material is added in different ratios.

[0095] Each Samples 14 to 16 has a high CuO content.

[0096] Additionally, Samples 1 to 13 use CuO powder having a meanparticle diameter of 0.5 to 2 μm and Samples 14 to 16 use powder havinga mean particle diameter of 8 μm.

[0097] More concretely, CuO powder (mean particle diameter: 0.5 to 2 μmor 8 μm) and the cooperative material consisting of the startingmaterials of the ceramic layer are blended and kneaded at blend ratiostabulated in Table 1 with an organic vehicle prepared by dissolvingethyl cellulose in terpineol and a resin agent (acrylic resin, arakydresin, docell resin, etc) to prepare the paste materials havingdifferent CuO contents.

[0098] Next, a laminate type dielectric device is produced in thefollowing way by using each of these electrode paste materials. In thisembodiment, however, the number of lamination of the dielectric ceramiclayers is 3 so that the section of the laminate type dielectric devicecan be easily observed.

[0099] First, a green sheet obtained by shaping the ceramic materialinto a sheet is produced by a doctor blade method.

[0100] Powders of lead oxide, zirconium oxide, titanium oxide, niobiumoxide, strontium carbonate, etc, as the main starting materials of thedielectric ceramic layer are weighed so as to attain a desiredcomposition. The lead content is weighed to be by about 1 to 2% richerthan the stoichiometric ratio of the mixture composition inconsideration of evaporation of lead. The mixture is dry mixed by usinga mixer and is then calcined at 800 to 900° C. (lower than the bakingtemperature).

[0101] Pure water and a dispersant are added to the powder so calcinedso as to form slurry. The resulting slurry is wet pulverized by using apearl mill. After the pulverizate is dried and degreased, a solvent, abinder, a plasticiser, a dispersant, etc, are added and mixed by using aball mill. The resulting slurry is vacuum defoamed and its viscosity isadjusted while the slurry is being stirred by using a stirrer inside avacuum apparatus.

[0102] Next, the slurry is shaped into a green sheet having apredetermined thickness by using a doctor blade.

[0103] After recovery, the green sheet is punched by using a puncher, oris cut by using a cutter, to give rectangular members having apredetermined size.

[0104] Next, the electrode paste material 2 of each of Sample 1 to 16 isscreen-printed into a pattern to one of the surfaces of two green sheets11 after shaping as shown in FIG. 1. In this embodiment, the printingthickness is 15 μm. The drawing shows an example of the green sheet 11after printing of the pattern.

[0105] Another green sheet 11, to which the electrode paste material 2is not printed, is added, and these three green sheets 11 are laminatedas shown in the drawing in such a fashion that the electrode pastematerials 2 alternately reach the right and left side surfaces.

[0106] After being bonded, the laminate product is cut into apredetermined size.

[0107] Next, the laminate product is heated in open air to 500° C. andis held for 5 hours for degreasing, and is then subjected to ametallizing process.

[0108] The metallizing process is the process that reduces CuO in theelectrode paste material to Cu in a reducing atmosphere at a relativelylow temperature. In this embodiment, since the ceramic material is theoxide containing lead at least from the aspect of the chemical formula,the reducing atmosphere is adjusted to a temperature immediately below326° C. as the eutectic point of lead and copper, and reduction iscarried out.

[0109] A baking process for integrally baking the laminate product isthen carried out. The baking temperature can be changed depending on thekind of the ceramic materials constituting the dielectric ceramic layer,and is set to 950° C. in this embodiment. This adjustment atmosphere isset to the atmosphere in which oxidation of Cu is less and the oxide ofthe device portion is not reduced as much as possible. The reducingpower is smaller than that of the metallizing process, and the oxygenpartial pressure varies depending on the baking temperature. In thisembodiment, the oxygen partial pressure is about 10⁻⁶ atm at 950° C.

[0110] A side electrode and an outer electrode are fitted depending onthe kind of the product.

[0111] The section of the laminate product (laminate type dielectricdevice 1) integrally baked as shown in FIG. 2 is observed in thisembodiment. The observation position exists at the center of the sectiontaken along a line III-III in FIG. 2.

[0112] FIGS. 3 to 12 represent schematic sketches of the observationresults.

[0113]FIG. 3 shows the observation result of Sample 1. The results ofSamples 2 to 6 are omitted because they as similar to the observationresult of Sample 1. As shown in the drawing, Samples 1 to 6 do not haveany voids and cracks in both electrode layer 2 and ceramic layer 11. Nopeeling develops at the boundary between them, and the bonding conditionis excellent.

[0114] The following observation can be acquired. In Samples 1 to 4, thetotal addition amount of CuO powder and the cooperative material isfixed at 69 wt %, and the addition amount of the cooperative material ischanged within the range of 1 to 8 wt % as tabulated in Table 1. Theresult is excellent even when the addition ratio of CuO and thecooperative material is changed within such a broad range. In Samples 2,5 and 6, the addition amount of the cooperative material is fixed at 4wt % and the content of CuO powder is changed within the range of 65 to69 wt %. The result is excellent even when the addition ratio of CuO ischanged within such a broad range.

[0115] On the other hand, Samples 7 to 10 do not contain the cooperativematerial as shown in FIGS. 4 to 7. In this case, voids 81 and cracks 82are likely to develop.

[0116] Sample 8 provides an excellent laminate type dielectric deviceeven when the cooperative material is not added, as shown in FIG. 5.However, a disadvantage occurs when the CuO content changes even to asmall extent. In other words, in the case of Sample 7 shown in FIG. 4,the voids 81 develop in the electrode layer 2 when the CuO contentdecreases by only 1 wt %, and in the case of Sample 9 shown in FIG. 6,the cracks 82 develop in the ceramic layer when the CuO contentincreases by only 1.5 wt %. When the CuO content increases by 4 wt % asin Sample 10, the occurrence of cracks 82 becomes greater as shown inFIG. 7.

[0117] It can be understood, from the comparison of Samples 1 to 6 withSamples 7 to 10, that, when the cooperative material is added, thelaminate type dielectric device can be obtained under excellentconditions even when the changes in CuO content is greater than 4 wt %,but when the cooperative material is not added, adverse influencesappear when the CuO content changes by only 1 wt %.

[0118] Next, in the case of Sample 11, the CuO content is decreased to50 wt % and the cooperative material is not added. In this case, a largenumber of voids 81 can be observed as shown in FIG. 8(a). In contrast,in the case of Sample 12, the CuO content is 50 wt %, and 6 wt % of thecooperative material is added. In this case, the thickness of theelectrode layer 2 becomes smaller than when the cooperative material isnot added as shown in FIG. 8(b), so that the number of voids 81decreases. However, when the content of the cooperative material isfurther increased as in Sample 13, portions 85 at which the electrodelayer 2 disappears occur as shown in FIG. 9.

[0119] This result represents that the problem cannot be solved by themere addition of the cooperative material alone.

[0120] Next, Samples 14 and 15 respectively use the paste materialprepared by mixing 3 wt % of the cooperative material, 19.5 wt % of theorganic vehicle and the resin and 77.5 wt % of CuO powder (8 μm), andthe paste material prepared by mixing 3 wt % of the cooperativematerial, 14.5 wt % of the organic vehicle and the resin and 82.5 wt %of CuO powder (8 μm) as tabulated in Table 1.

[0121] Large cracks are not observed in the ceramic layer 11 in Sample14 as shown in FIG. 10. On the other hand, cracks 82 are partiallyobserved in Sample 15. It can be estimated from this result that the CuOcontent of Sample 14 is the boundary of the CuO content at which theformation of voids in the electrode portion changes to the occurrence ofcracks in the ceramic layer, that is observed due to the difference ofthe CuO content. In Sample 14, however, though the electrode portion iscontinuous and no cracking occurs in the ceramic layer, peeling 83occurs at the boundary between the electrode portion and the ceramiclayer as shown in FIG. 10.

[0122] As shown in FIG. 12, further, enlarged peeling 83 occurs in thecase of the electrode paste material of Sample 16 prepared by mixing17.5 wt % of the organic vehicle and the resin and 82.5 wt % of CuOpowder (8 μm) without adding the cooperative material.

[0123] Incidentally, the differences in Samples 1 to 3 are the particlediameter of CuO contained and the CuO content adjusted. Since the CuOcontent is adjusted so as to prevent the formation of voids in theelectrode portion and the occurrence of cracks in the ceramic layer, theparticle diameter is preferably less than 8 μm in the production processrepresented in this embodiment.

[0124] Embodiment 2:

[0125] This embodiment uses the materials of Sample 14 of Embodiment 1,i.e. [paste material prepared by mixing cooperative material: 3 wt %,organic vehicle and resin: 19.5 wt %, CuO powder (8 μm): 77.5 wt %], andproduces a laminate type dielectric device in the same way as inEmbodiment 1 with only the exception that the metallizing step isomitted. The observation result of the section conducted in the same wayas in Embodiment 1 is shown as a schematic view in FIG. 13.

[0126] As can be seen from the drawing, peeling does not occur betweenthe electrode layer and the ceramic layer, and the voids of theelectrode portion can be restricted to a considerable extent. It can beconcluded from the result of this embodiment that the problem of peelresulting from the difference of the particle diameters can be solveddepending on the production process.

[0127] However, it can be estimated that when the particle diameter isextremely great in comparison with the thickness of the electrode layer,the electrode layer cannot be formed to a flat layer. Therefore, thelimit condition of the particle diameter may well be such that it is notmuch greater than the thickness of the intended electrode layer.

[0128] It is estimated that peeling in Samples 14, 15 and 16 occurs forthe following reasons. Though the reaction starting temperature betweenthe electrode portion and the ceramic layer is low as in the prior arttechnology, the specific surface area of the electrode materialdecreases with the result that the reaction rate on the entire surfaceof the boundary between the ceramic layer and the electrode portion (theboundary surface to which printing is not made particularly) isretarded. To avoid peeling, therefore, it is possible to employ a methodthat brings the condition of the boundary portion between the ceramiclayer having a slow sintering behavior and the electrode material intoan easily bondable condition, and that utilizes the properties of theelectrode material having high thermal conductivity and high reactionrate. For example, when the electrode material is printed on bothsurface of the ceramic layer and then lamination, degreasing,metallizing and baking are conducted, the members that come into mutualcontact during lamination are only the electrode materials, and thereaction proceeds rapidly. On the other hand, the boundary portionbetween the electrode material and the ceramic layer keeps the contactstate at the time of printing and is subjected to degreasing,metallizing and baking, and can be bonded relatively easily.

[0129] Embodiment 3:

[0130] This embodiment overcomes the problems (the occurrence of voidsand peel) in the construction of the paste materials that cannot formboth electrode layer and ceramic layer without voids and peel inEmbodiment 1, by conducting printing a plurality of times.

[0131] The paste material comprises 45 wt % of the organic vehicle andthe resin, 40 wt % of CuO (mean particle diameter: 0.5 to 2 μm) and 15wt % of the cooperative material (Sample 17).

[0132] In Embodiments 1 and 2, drying is conducted at 80° C. for 10minutes after printing. In this embodiment, after drying is conducted at80° C. for 10 minutes, the electrode paste material is again applied,and drying is conducted at 100° C. for 20 minutes. The subsequentprocess steps are the same as those of Embodiments 1 and 2.

[0133] As a result, a laminate type dielectric device free from voidsand peel in both electrode and ceramic layers can be obtained in thesame way as in Sample 1 shown in FIG. 3.

[0134] In Samples 18 and 19 each having the construction listed below,application and drying are repeated a plurality of times in the same wayas in Sample 17, but the occurrence of voids in the electrode layer ordisappearance of the electrode layer, as shown in FIG. 9, isunavoidable.

[0135] Sample 18:

[0136] vehicle and resin: 55 wt %, CuO (mean particle diameter: 0.5 to 2μm): 30 wt %, cooperative material: 15 wt %

[0137] Sample 19:

[0138] vehicle and resin: 35 wt %, CuO (mean particle diameter: 0.5 to 2μm): 40 wt %, cooperative material: 25 wt %

[0139] Sample 18 has a smaller CuO content of 30 wt % in comparison withthe CuO content 40 wt % of Sample 17. In other words, the lower limit ofthe CuO content is 30 to 40 wt %.

[0140] Sample 19 has a greater content of the cooperative material of 25wt % than the content 15 wt % of Sample 17. In other words, the upperlimit of the cooperative material is 15 to 25 wt %.

[0141] Embodiment 4:

[0142] This embodiment represents an example of a piezoelectric actuator10 produced by using the electrode paste material shown in Embodiment 1.

[0143] This piezoelectric actuator 10 is produced by alternately forminginner electrode layers (electrode layers) 21 and 22 to positive andnegative between piezoelectric layers (ceramic layers) 11 as shown inFIG. 14. One 21 of the inner electrode layers is so disposed as to beexposed on one 101 of the side surfaces while the other inner electrodelayer 22 is so disposed as to be exposed to the other side surface 102.Outer electrodes 31 and 32 are formed on the side surfaces 101 and 102of the piezoelectric device 10 by baking silver in such a fashion as toelectrically connect the end portions of the exposed inner electrodelayers 21 and 22, respectively.

[0144] Baked silver that forms the outer electrodes 31 and 32 is theelectrodes formed by baking an Ag paste, and has a compositionconsisting of Ag (97%) and a glass frit component (3%) as will bedescribed later.

[0145] Outer electrodes are bonded respectively onto the outerelectrodes 31 and 32 by using resin with silver (not shown in thedrawing). Resin silver for bonding the outer electrodes has acomposition consisting of 80% of Ag and 20% of an epoxy resin.

[0146] In the piezoelectric actuator 10, the center portion in thelaminating direction is a driving portion 111, portions so arranged asto sandwich the driving portion are buffer portions 112 and portions soarranged as to further sandwich the buffer portions 112 are dummyportions 113.

[0147] It is noteworthy that the paste of Sample 2 of Embodiment 1 isused as the electrode paste material for forming the inner electrodelayers 21 and 22. The piezoelectric actuator 10 obtained after baking isfree from the voids and cracks in the ceramic layer and in the electrodelayer, is also free from peeling between them, and has excellentquality.

[0148] However, the side electrode material is not limited to Ag, andany one of Cu, Pt, Ni and Pd may be contained.

[0149] Though this embodiment represents the piezoelectric actuator, ahigh quality product can also be obtained in a laminate type ceramiccapacitor by using the excellent electrode paste material describedabove.

[0150] Embodiment 5:

[0151] In this embodiment, Sample 20 shown in Table 1 is prepared. InSample 20, the total weight of CuO powder (mean particle diameter: 0.5to 2 μm) and the cooperative material is kept constant at 69 wt % with68.5 wt % of CuO powder and 0.5 wt % of the cooperative material. Thesection is observed for this Sample 20, too, in the same way as inEmbodiment 1. As a result, the size and number of the cracks is similarto that of Sample 10 as shown in FIG. 7.

[0152] In other words, the improving effect cannot be observed even whenabout 0.5 wt % of the cooperative material is added. Therefore, it ispreferred to add at least 0.5 wt % of the cooperative material.

[0153] Embodiment 6:

[0154] This embodiment represents the case where the electrode pastematerial contains not only CuO powder but also Cu powder.

[0155] In this embodiment, twenty kinds of samples (Samples 21 to 40)are prepared as shown in Table 2. In each sample, about a half of theamount of CuO powder in Samples 1 to 20 in Embodiments 1 and 5 isreplaced by Cu powder.

[0156] The starting materials have the same properties as the materialsconstituting Samples 1 to 20.

[0157] Cu powder contained in Samples 21 to 33 and 37 to 40 is preparedby crushing Cu particles having a mean particle diameter of 0.5 μmbefore crushing into powder having a sheet form. Further, Cu particleshaving a mean particle diameter of 2.0 μm is used in Samples 34 to 36.The production condition of each sample is the same as that ofEmbodiment 1 with the exception of the metallizing step.

[0158] Whereas the metallizing condition is at immediately below 326° C.for 10 hours in Embodiment 1, it is immediately below 326° C. for 5hours in this embodiment.

[0159] The section of each of the resulting three-layered laminateproducts (Samples 21 to 40) is observed in the same way as inEmbodiment.

[0160] The observation results of Samples 21 to 26 are the same as thatof Sample 1 shown in FIG. 3. As shown in the drawing, all the Samples 21to 26 are free from voids and cracks in both electrode layer 2 andceramic layer 11, and peel does not occur at their boundary portion.Thus, the excellent bonding condition can be obtained in all cases.

[0161] Here, the following observation can be made. In Samples 21 to 24,while the total addition amount of CuO powder, Cu powder and thecooperative material is kept fixed at 69 wt % as shown in Table 2 (theCu powder amount is represented by a numeric value after conversion tothe CuO amount by the ratio of the molecular weight; hereinafter thesame), the addition amount of the cooperative material is changed withinthe range of 1 to 8 wt %. In other words, the addition proportion ofCuO, Cu and the cooperative material is changed in a broad range. InSamples 22, 25 and 26, further, the addition amount of the cooperativematerial is kept fixed at 4 wt %, and the total amount of CuO powder andCu powder is changed within the range of 65 to 69 wt % as shown in Table2. Good results can be obtained when the addition proportion of CuO andCu is changed in such a broad range.

[0162] On the other hand, Samples 27 to 30 of this embodiment do notcontain the cooperative material in the same way as in Samples 7 to 10(Embodiment 1) shown in FIGS. 4 to 7. In this case, voids 81 and cracks82 are more likely to develop.

[0163] Sample 28 provides a good laminate type dielectric device eventhough it does not contain the cooperative material in the same way asSample 8 (Embodiment 1) shown in FIG. 5, but when the total content ofCuO and Cu changes even slightly from this sample, disadvantages occur.In other words, in the case of Sample 27, the voids 81 develop in theelectrode layer 2 when the total content of CuO and Cu decreases by only1 wt % (see FIG. 4). In Sample 29, the cracks 82 develop in the ceramiclayer when the total content of CuO and Cu increases by only 1.5 wt %(see FIG. 6). when the total content of CuO and Cu increases by 4 wt %as in Sample 30, the occurrence of the cracks 82 becomes more remarkablein the same way as in FIG. 7.

[0164] It can be understood by comparing Samples 21 to 26 with Samples27 to 30 that good laminate type dielectric devices can be obtained evenwhen the change of the total content of CuO and Cu exceeds 4 wt % if thecooperative material is contained. However, when the cooperativematerial is not contained, the change of only 1 wt % of the totalcontent of CuO and Cu exerts an adverse influence.

[0165] Next, Sample 31 represents the example where the total content ofCuO and Cu is decreased to 50 wt % and the cooperative material is notadded. In this case, a large number of voids 81 are seen occurring inthe same way as the example shown in FIG. 8(a). In contrast, Sample 32represents the example where the total content of CuO and Cu is 50 wt %and 6 wt % of the cooperative material is contained. In this case, thethickness of the electrode layer 2 becomes smaller than the electrode 2without addition of the cooperative material in the same way as in theexample shown in FIG. 8(b), so that the occurrence of voids 81 becomesless. When the content of the cooperative material is further increasedas in Sample 33, however, the portions 85 where the electrode layer 2disappears take place in the same way as in the example shown in FIG. 9.

[0166] These results represent that the problems cannot be solved by themere addition of the cooperative material.

[0167] Next, Samples 34 and 35 respectively use the paste materialprepared by mixing 3 wt % of the cooperative material, 19.5 wt % of theorganic vehicle and the resin, 35 wt % of CuO powder (8 μm) and 42.5 wt%, calculated as CuO, of Cu powder (2 μm), and the paste materialprepared by mixing 3 wt % of the cooperative material, 14.5 wt % of theorganic vehicle and the resin, 40 wt % of CuO powder (8 μm) and 42.5 wt%, calculated as Cuo, of Cu powder (2 μm).

[0168] In Sample 34, large cracks are not observed in the ceramic layer11 in the same way as in the example shown in FIG. 10. In Sample 35, onthe other hand, cracks 82 are partly observed in the same way as in theexample shown in FIG. 11. It can be estimated from this result that thetotal content of CuO and Cu of Sample 34 is near the boundary of thetotal content of CuO and Cu at which the formation of the voids in theelectrode portion shifts to the occurrence of the cracks in the ceramiclayer, that is observed in the change of the difference of the totalcontent of CuO and Cu. In Sample 34, however, the electrode portion iscontinuous and the cracks do not occur in the ceramic layer, but peeling83 develops at the boundary between the electrode portion and theceramic layer as shown in FIG. 10.

[0169] In the case of the electrode paste material of Sample 36 that isprepared by mixing 17.5 wt % of the organic vehicle and the resin and82.5 wt % of CuO powder and Cu powder in the amount calculated as theamount of CuO powder on the basis of the molecular weight, without thecooperative material, in the same way as the example shown in FIG. 12,too, greater peeling 83 occurs.

[0170] The differences from Samples 21 to 23 are the particle diametersof CuO and Cu and the total contents of CuO and Cu adjusted. Since thetotal content of CuO and Cu is adjusted so as to prevent the formationof voids in the electrode portion and the occurrence of cracks in theceramic layer, the particle size in the production process of thisembodiment is preferably less than 8 μm. TABLE 2 (wt %) Cu powder(numeric organic value after vehicle and conversion cooperative SampleNo. resin to CuO) CuO powder material 21 31.0 31.0 30.0 8.0 22 31.0 33.032.0 4.0 23 31.0 36.0 30.0 3.0 24 31.0 37.0 31.0 1.0 25 29.0 34.0 33.04.0 26 27.0 38.0 31.0 4.0 27 36.0 34.0 30.0 nil 28 35.0 36.0 29.0 nil 2933.5 34.5 32.0 nil 30 31.0 34.0 35.0 nil 31 50.0 25.0 25.0 nil 32 44.025.0 25.0 6.0 33 40.0 25.0 25.0 10.0 34 19.5 42.5 35.0 3.0 35 14.5 42.540.0 3.0 36 17.5 42.5 40.0 nil 37 45.0 20.0 20.0 15.0 38 55.0 11.0 19.015.0 39 35.0 20.0 20.0 25.0 40 31.0 37.5 31.0 0.5

[0171] Embodiment 7:

[0172] In this embodiment, a laminate type dielectric device is producedby using the material of Sample 34 of Embodiment 6 (paste materialprepared by mixing 3 wt % of cooperative material, 19.5 wt % of organicvehicle and resin and 77.5 wt % of CuO powder and Cu powder) in the sameway as in Embodiment 6 with the exception that only the metallizing stepis omitted.

[0173] In the same way as in the example shown in FIG. 13, peeling isnot observed between the electrode layer and the ceramic layer, and thevoids of the electrode layer are restricted to a considerable extent. Itcan be concluded from the result of this embodiment that the problem ofpeeling resulting from the difference of the particle diameters can besolved depending on the production process.

[0174] However, it can be estimated that the electrode layer cannot beproduced in a flat form if the particle diameter is much greater thanthe thickness of the electrode layer. Therefore, it will be sufficientthat the particle diameter is not much greater than the intendedelectrode layer as the limiting condition of the particle diameter.

[0175] Peeling in Samples 34, 35 and 36 presumably occurs because thespecific surface area of the electrode material drops though thereaction starting temperature between the electrode portion and theceramic layer remains low in the same way as in the prior arttechnologies, and promotion of the reaction on the entire boundarysurface between the ceramic layer and the electrode layer (particularly,the boundary surface that is not printed) is retarded. Therefore, toavoid peeling, it is possible to use a method that brings in advance theboundary portion between the ceramic layer having a low sinteringbehavior and the electrode material into an easily bondable condition,and utilizes the properties of the electrode materials having highconductivity and a high reaction rate. For example, when the electrodematerial is in advance printed and laminated on both surfaces of theceramic layer and thereafter degreasing, metallizing and baking areconducted, it is the printed electrode materials that come into mutualcontact at the time of lamination, and the reaction rapidly proceeds atthe time of heating. On the other hand, one side of the boundary portionbetween the electrode material and the ceramic layer is relativelyeasily bondable because degreasing, metallizing and baking are conductedwhile the contact condition at the time of printing is kept as such.

[0176] Embodiment 8:

[0177] This embodiment solves the problems (occurrence of voids andpeeling) by use of the construction of the paste material, which cannotform both electrode and ceramic layers without inviting voids and peelin Embodiment 6, by conducting printing a plurality of times.

[0178] The base material consists of 45 wt % of the organic vehicle andthe resin, 40 wt % of CuO and Cu and 15 wt % of the cooperative material(Sample 37).

[0179] In Embodiments 6 and 7, drying is conducted at 80° C. for 10minutes after printing. In this embodiment, after drying is conducted at80° C. for 10 minutes, the electrode paste material is again applied,and drying is conducted at 100° C. for 20 minutes. The subsequentprocess steps are the same as those of Embodiments 5 and 6.

[0180] As a result, this embodiment can obtain a laminate typedielectric device free from voids and peel in both electrode and ceramiclayers in the same way as Sample 1 shown in FIG. 3.

[0181] In Samples 38 and 39 each having the construction listed below,application of the paste material and drying are carried out a pluralityof times in the same way as Sample 37, but the occurrence of voids inthe electrode layer or disappearance of the electrode layer(interruption; the same as in FIG. 9) cannot be avoided.

[0182] Sample 38:

[0183] organic vehicle and resin: 55 wt %, CuO and Cu: 30 wt %,cooperative material: 15 wt %

[0184] Sample 39:

[0185] organic vehicle and resin: 35 wt %, CuO and Cu: 40 wt %,cooperative material: 25 wt %

[0186] In comparison with Sample 37, Sample 38 has smaller Cu and CuOcontents, that is, 30 wt %, with respect to 40 wt % of the former. Inother words, the lower limit of the Cu and CuO contents is 30 to 40 wt%.

[0187] In comparison with Sample 37, Sample 39 has a greater content ofthe cooperative material, that is, 25 wt %, with respect to 15 wt % ofthe former. In other words, the upper limit of the cooperative materialis 15 to 25 wt %.

[0188] Embodiment 9:

[0189] In this embodiment, the section of Sample 40 shown in Table 2 isobserved in the same way as in Embodiment 6. In Sample 40, the totalweight of CuO powder, Cu powder and the cooperative material is keptconstant at 69 wt % in the same way as Samples 21 to 24 in Embodiment 6,and the content of CuO powder and Cu powder is set to 68.5 wt % and thecooperative material, to 0.5 wt %. As a result of observation of thesection of this Sample 40, the size and number of cracks are the same asthose of Sample 10 as shown in FIG. 7.

[0190] In other words, even when both CuO powder and Cu powder arecontained, the improving effect cannot be recognized when about 0.5 wt %of the cooperative material is added. It is therefore preferred to addat least 0.5 wt % of the cooperative material.

What is claimed is:
 1. An electrode paste material for constitutingelectrode layers of a laminate type dielectric device produced by atleast the steps of alternately laminating ceramic layers containing leadas a constituent component and the electrode layers, and degreasing andbaking the laminate, wherein said electrode paste material contains CuOas a principal component of a starting material of an electricallyconductive material, a solvent, a binder, and a cooperative materialconsisting of at least one kind of the main components constituting saidceramic layer.
 2. An electrode paste material according to claim 1,wherein said cooperative material has substantially the same compositionas said ceramic layer.
 3. An electrode paste material according to claim1, wherein the content of CuO is greater than 30 wt % but less than 82.5wt %, and the content of said cooperative material is greater than 0.5wt % but less than 25 wt %.
 4. An electrode paste material according toclaim 3, wherein the content of CuO is not less than 40 wt % but notgreater than 77.5 wt %.
 5. An electrode paste material according toclaim 3, wherein the content of said cooperative material is not lessthan 1 wt % but not greater than 15 wt %.
 6. A method of producing alaminate type dielectric device by at least the steps of alternatelylaminating ceramic layers containing a lead element as a constituentcomponent and electrode layers, and degreasing and baking the laminate,comprising: preparing green sheets obtained by shaping a ceramicmaterial into a sheet form, and an electrode paste material containingCuO as a principal component of a starting material of an electricallyconductive material, a solvent, a binder, and a cooperative materialconsisting of at least one kind of the main components constituting saidceramic layer; applying said electrode paste material to at least one ofthe surfaces of said plurality of green sheets; and laminating saidgreen sheets, and then conducting degreasing and baking.
 7. A method ofproducing a laminate type dielectric device according to claim 6,wherein the application of said electrode paste material is made to bothsurfaces of said green sheets, and said electrode paste material isbrought into mutual contact in said lamination step.
 8. A method ofproducing a laminate type dielectric device according to claim 7,wherein a metal foil having electric conductivity is interposed betweensaid electrode paste materials.
 9. A method of producing a laminate typedielectric device according to claim 6, wherein said cooperativematerial has substantially the same composition as said ceramic layer.10. A method of producing a laminate type dielectric device according toclaim 6, wherein the content of CuO is greater than 30 wt % but lessthan 82.5 wt %, and the content of said cooperative material is greaterthan 0.5 wt % but less than 25 wt %.
 11. A method of producing alaminate type dielectric device according to claim 10, wherein thecontent of CuO is not less than 40 wt % but not greater than 77.5 wt %.12. A method of producing a laminate type dielectric device according toclaim 10, wherein the content of said cooperative material is not lessthan 1 wt % but not greater than 15 wt %.
 13. A method of producing alaminate type dielectric device according to claim 6, wherein saidceramic layer is mainly made of an oxide having a Pb(Zr, Ti)O₃ typeperovskite structure.
 14. An electrode paste material for constitutingelectrode layers of a laminate type dielectric device produced by atleast the steps of alternately laminating ceramic layers containing alead element as a constituent component and the electrode layers, anddegreasing and baking the laminate, wherein said electrode pastematerial contains CuO and Cu as principal components of a startingmaterial of an electrically conductive material, a solvent, a binder,and a cooperative material consisting of at least one kind of the maincomponents constituting said ceramic layer.
 15. An electrode pastematerial according to claim 14, wherein said cooperative material hassubstantially the same composition as said ceramic layer.
 16. Anelectrode paste material according to claim 14, wherein the totalcontent of CuO and Cu is greater than 30 wt % but less than 82.5 wt %calculated to CuO in terms of the ratio of the molecular weight, and thecontent of said cooperative material is greater than 0.5 wt % but lessthan 25 wt %.
 17. An electrode paste material according to claim 16,wherein the total content of CuO and Cu is not less than 40 wt % but notgreater than 77.5 wt % calculated to CuO in terms of the ratio of themolecular weight.
 18. An electrode paste material according to claim 16,wherein the content of said cooperative material is not less than 1 wt %but not greater than 15 wt %.
 19. A method of producing a laminate typedielectric device by at least the steps of alternately laminatingceramic layers containing a lead element as a constituent component andelectrode layers, and degreasing and baking the laminate, comprising:preparing green sheets obtained by shaping a ceramic material into asheet form, and an electrode paste material containing CuO and Cu asprincipal components of a starting material of an electricallyconductive material, a solvent, a binder, and a cooperative materialconsisting of at least one kind of the main components constituting saidceramic layer; applying said electrode paste material to at least one ofthe surfaces of said plurality of green sheets; and laminating saidgreen sheets, and then conducting degreasing and baking.
 20. A method ofproducing a laminate type dielectric device according to claim 19,wherein the application of said electrode paste material is made to bothsurfaces of said green sheets, and said electrode paste material isbrought into mutual contact in said lamination step.
 21. A method ofproducing a laminate type dielectric device according to claim 20,wherein a metal foil having electric conductivity is interposed betweensaid electrode paste materials.
 22. A method of producing a laminatetype dielectric device according to claim 19, wherein said cooperativematerial has substantially the same composition as said ceramic layer.23. A method of producing a laminate type dielectric device according toclaim 19, wherein the total content of CuO and Cu is greater than 30 wt% but less than 82.5 wt % calculated to CuO in terms of the ratio of themolecular weight, and the content of said cooperative material isgreater than 0.5 wt % but less than 25 wt %.
 24. A method of producing alaminate type dielectric device according to claim 23, wherein the totalcontent of CuO and Cu is not less than 40 wt % but not greater than 77.5wt % calculated to CuO in terms of the ratio of the molecular weight.25. A method of producing a laminate type dielectric device according toclaim 23, wherein the content of said cooperative material is not lessthan 1 wt % but not greater than 15 wt %.
 26. A method of producing alaminate type dielectric device according to claim 19, wherein saidceramic layer is mainly made of an oxide having a Pb(Zr, Ti)O₃ typeperovskite structure.